A battery module includes a plurality of battery cells connected in series. However, in practical application of the battery module, voltages of the battery cells are not exactly the same. Especially, after multiple charging and discharging of the battery module, there is a more obvious difference between voltages of different battery cells, which affects life and safety of the battery module.
Usually, an equalization circuit is used to solve the problem of voltage non-uniformity of battery cells in the battery module. However, if the equalization circuit is in malfunction, equalization effect by the equalization circuit will be affected.